Waters Corp. says it will restate unaudited financial statements for the first three quarters of its 2007 fiscal year to reclassify marketable securities on its balance sheet.

The company classified as cash and cash equivalents securities that should have been classified as short-term investments, based on the length of time from original purchase date to maturity date. The revisions will reduce cash and cash equivalents by a total of $368 million over the nine-month period.

The changes were a result of an internal control that was not operating effectively, the thermal-analysis company concedes. “The same internal control did operate effectively in the fourth quarter of 2007 and ultimately detected the change in classification required to the first three quarters of 2007,” it adds.

The change does not affect the unaudited consolidated statements of operations, Waters says, nor does it have an impact on previously reported current assets, total assets, stockholders’ equity, cash flows from operating activities, or cash flows from financing activities.